A developed process for deep drawing of metal foil square cups M.A. Hassan, K.I.E. Ahmed, N. Takakura Metal foils have been used for micro-electro-mechanical systems (MEMS), electronic components (e.g. lead frames) and in medical devices. Deep drawing of square cups from thin sheets or metal foils has become increasingly important. However, the current conventional deep drawing processes are unable to offer reasonable drawing ratios in this condition due to the early localized wrinkling formations and/or the cup corner fractures before any cup wall formation occurs. Many attempts have been made to increase the limiting drawing ratio of foil cups produced from thin sheets. Marumo et al. (2001) have investigated the deep drawing of nickel foil cylindrical cups. In their experimental they used a lapfoil- blank, in which thin sheets from polyethylene, Nylon 66 and aluminum were sued for lapping over nickel foil to control its flow stress in the range below the ultimate strength and suppress wrinkling of foil. This technique has shown slight improvement in the drawability of the nickel foil. Yasuo et al. (2005) have studied the effect of the loading paths of blank holding pressure on the limiting drawing ratio in deep drawing of metal foils to cylindrical cups. Pure copper foils were used in their experiments together with a PTFE die and a Nylon 66 auxiliary sheet to support the blank foil. They found that the blank holding pressure required for the elimination of wrinkling increases rapidly as the foil thickness decreases. Wrinkling was effectively prevented; however with insignificant increase in limiting drawing ratio (LDR) of pure cupper foils, because the Nylon 66 auxiliary sheet and the foil blank were together subjected to ironing during deep drawing. The process proposed by Maslennikov (1957) is good for deep drawing of aluminum and copper thin sheets. In this process, a rubber ring, held in a container, is skillfully utilized as a pressure medium and a forming tool as well. The sheet is drawn radially inwards by friction force induced at the contact surface between the blank sheet and the rubber ring. In this process very deep cups with high drawing ratio can be obtained. However, for very thin sheets and foils, circumferential fracture has been observed at the flange portion during deep drawing of circular section cups.